Having a single Domain Controller can be quite risky because in case of any kind of hardware or some other technical failure, the entire network can be destroyed.
Recently, we wrote a guide on How to create a Domain in Windows Server 2008, in this post we will tell you how to create a backup Domain or an Additional Domain Controller (ADC).
Having an ADC means that in case your primary Domain fails, it takes over the functions of the Primary Domain and keeps the network functional.
Client operating systems in this scenario do not get disconnected and a complete network failure is hence, avoided.
Moreover, one or more ADCs can help in balancing load of the Domain, fault tolerance and to improve the availability and reliability of network services.
Before going into the topic let’s learn something about the Latest Release of Windows Server 2016
Let’s get into our current post
To get started, go to the command prompt or Run, type dcpromo and hit Enter. Whether you are making a Domain, Child Domain, ADC or removing any of them, the dcpromo command is used.
The system will start checking if Active Directory Domain Services ( AD DS) binaries are installed, then will start installing them. The binaries could be installed if you had run the dcpromo command previously and then canceled the operation after the binaries were installed.
The Active Directory Domain Services Installation Wizard will start, either enable the checkbox beside Use Advanced mode installation and Click Next , or keep it unselected and click on Next
The Operating System Compatibility page will be displayed, take a moment to read it and click Next
This is the Important Steps in configuring ADC – Choose a Deployment Configuration page, click Existing forest, click Add a domain controller to an existing domain, and then click Next.
On the Network Credentials page, type your domain name, my domain name i have used here and in my last post is DoubtsClear.com
This will prompt you to enter credentials to connect to the Domain.
Note: the credentials must have administrative privileges. In this case I am using an account that is apart of the Domain Controllers group. After verifying the information, the wizard will allow you to proceed further. Click Next to continue.
To enter the Alternate credentials, click Set. In the Windows Security dialog box, enter the user name and password for an account that must be either a member of the Enterprise Admins group or the Domain Admins group > then click Next.
On the Select a Domain page, select the domain of the Additional Domain Controller, and then click Next, as I already have only one domain, then it will be selected by default.
On the Select a Site page, either enable the checkbox beside Use the site that corresponds to the IP address of this computer, this will install the domain controller in the site that corresponds to its IP address, or select a site from the list and then click Next.
If you only have one domain controller and one site, then you will have the first option grayed and the site will be selected by default as shown in the following image
On the Additional Domain Controller Options page, By default, the DNS Server and Global Catalog checkboxes are selected
Note: do not check RODC.
If you select the option to install DNS server in the previous step, then you will receive a message that indicates a DNS delegation for the DNS server could not be created and that you should manually create a DNS delegation to the DNS server to ensure reliable name resolution. If you are installing an additional domain controller in either the forest root domain (or a tree root domain) , you do not need to create the DNS delegation. In this case, you can safely ignore the message and click Yes.
In the Install from Media page ( will be displayed if you have selected Use advanced mode installation on the Welcome page, if you didn’t select it, then skip to location for the database, SYSVOL), you can choose to either replicate data over the network from an existing domain controller, or specify the location of installation media to be used to create the domain controller and configure AD DS. I want to replicate data over the network, so I will choose the first option > click Next
On the Source Domain Controller page of the Active Directory Domain Services Installation Wizard, you can select which domain controller will be used as a source for data that must be replicated during installation, or you can have the wizard select which domain controller will be used as the source for this data.
You have two options :
- Let the wizard choose an appropriate domain controller
- Use this specific domain controller
Just like when creating a Domain, you will get the choice to set a location for the database, SYSVOL and NTDS files. You may change the destination or let them remain in the default location and proceed to the next step.
Moving forward, you will be asked to save a restore mode password (which is separate from the Domain Administrator’s account). As mentioned in the previous post, this password is configured to be used when the Domain Controller is started in Directory Services Restore Mode. Choose a password and click Next.
Make sure the password meet the password complexity requirements of the password policy, that is a password that contains a combination of uppercase and lowercase letters, numbers, and symbols.
else you will receive the following message :
Finally, you will be presented with a summary of the selected options which you can review before moving forward.
Active Directory Domain Services installation will be completed, click Finish, then click on Restart Now to restart your server for the changes to take effect.
Open Active Directory Users & Computers, and then click on the Domain Controllers Organizational Unit, and you will see your Additional Domain Controller along with your Primary Domain Controller.
Here are the Links to complete Details about the Active Directory concepts and installations procedures.
- How to Install Active Directory on Windows Server 2008
- Creating a New Child Domain in Windows Server 2008
- Steps for Deploying & Installing an Read-Only Domain Controller (RODC)